The present disclosure relates to a cleaning device that removes toner left unused on the surface of an image carrying member by use of a cleaning member, and to an image forming apparatus incorporating such a cleaning device.
Conventionally, there is known an image forming apparatus of an intermediate transferring type that includes an endless intermediate transfer belt rotated in a predetermined direction and a plurality of image forming portions arranged along the intermediate transfer belt and that, after primary transferring by sequentially superimposing toner images of different colors to the intermediate transfer belt by the image forming portions, secondarily transfers them to a recording medium.
In such an image forming apparatus of the intermediate transferring type, a belt cleaning device is provided which removes toner left unused on the intermediate transfer belt after secondary transferring. If the intermediate transfer belt has no elastic layer, a blade type construction is used in which toner is scraped off while a cleaning blade is pressed onto the surface of the intermediate transfer belt.
On the other hand, if the intermediate transfer belt has an elastic layer, a cleaning device is frequently used which includes, in a housing, a cleaning blush that collects toner left unused on the surface of the intermediate transfer belt mechanically and electrically, a collection roller that collects toner from the cleaning brush, a blade that scrapes off toner from the surface of the collection roller, and a conveying spiral that conveys toner scraped off the surface of the collection roller to a waste toner container.
For example, there is known a belt cleaning device having a sheet member that divides the interior of a housing into a cleaning brush side and a conveying spiral side. The sheet member keeps its tip-end part in contact with the collection roller on the upstream side of a blade that scrapes off toner from the surface of the collection roller, and thereby guides toner scraped off the surface of the collection roller by the blade to the conveying spiral side so as not to return the toner to the cleaning brush side (outside the housing).
In this belt cleaning device, the intermediate transfer belt and the collection roller are so configured that, during their initial use, their surface roughness degreases through great secular change. This helps archive both toner scraping performance of the blade from the collection roller and paper particle conveying performance of the collection roller.
There is also known a cleaning device including a collection roller of which the surface roughness in both end parts in the axial direction is higher than the surface roughness in the middle part in the axial direction. In this cleaning device, the collection roller is given a low surface roughness in a region (a middle part in the axial direction) where it frequently scrapes off toner and a high surface roughness in other regions (both end parts in the axial direction). As a result, it is possible to satisfactorily collect toner from the cleaning member with the collection roller and to reduce adhesion between the blade and the collection roller over the entire range in the axial direction.